Technical Field
The present invention relates to a method of polymerizing ethylene in the presence of a catalyst composition containing BaFe12O19 nanofiller, a metallocene catalyst, and an alkylaluminoxane co-catalyst. The disclosure further includes a catalytic composition that includes a metallocene, a barium ferrite nanofiller and an alkylaluminoxane co-catalyst. Furthermore, the effect of the barium ferrite nanofiller on the catalytic activity of the metallocene polymerization catalyst and the properties of the resulting polyethylene/barium ferrite nanocomposite are disclosed.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
The field of olefin polymerization catalysis has accelerated in recent years, leading to the production of polymers with specific characteristics and many practical applications [W. Kaminsky, Macromol. Chem. Phys. 209 (2008) 459; V. C. Gibson, S. K. Spitzmesser, Chem. Rev. 103 (2003) 283—each incorporated herein by reference in its entirety]. Among olefin polymerization catalysts, metallocene complexes have proven to be some of the most versatile catalysts, while also providing high levels of polymer structure control [S. H. Abdul Kaleel, B. Kottukkal Bahuleyan, S. K. De, M. Jabarulla Khan, R. Sougrat, M. A. Al-Harthi, J. Ind. Eng. Chem. 18 (2012) 1836—incorporated herein by reference in its entirety]. For example catalytic activity, molar mass and molar mass distribution can be tuned by changes in the ligand and the metal center [V. C. Gibson, S. K. Spitzmesser, Chem. Rev. 103 (2003) 283; T. U. Berlin, F. V. Berlin, 501 (1995) 219—each incorporated herein by reference in its entirety]. Similarly, the steric and electronic effects of metallocene complexes can be tuned by altering the substitution patterns around the two aromatic ligands [H. G. Alt, a Köppl, Chem. Rev. 100 (2000) 1205—incorporated herein by reference in its entirety]. Recently, research efforts have shifted towards the use of nanomaterials to enhance the catalytic activity of metallocene complexes and to improve the properties of the resulting polymers. One such strategy to improve polymer properties involves an in-situ polymerization method, which results in better dispersion of nanofiller throughout the polymer matrix. In-situ polymerization also provides new scientific knowledge about the effect of nanofiller on the activity and chemistry of polymerization catalysts [E. Chaichana, B. Jongsomjit, P. Praserthdam, Chem. Eng. Sci. 62 (2007) 899—incorporated herein by reference in its entirety]. For instance the steric effect of graphene and CNTs can be utilized to tune the molecular weight, MWD and catalytic activity of single site catalysts [M. Stürzel, F. Kempe, Y. Thomann, S. Mark, M. Enders, R. Mülhaupt, Macromolecules 45 (2012) 6878; S. Park, S. W. Yoon, K.-B. Lee, D. J. Kim, Y. H. Jung, Y. Do, H. Paik, I. S. Choi, Macromol. Rapid Commun. 27 (2006) 47—each incorporated herein by reference in its entirety]. Studies on the effect of nano-Titania (TiO2) have shown that anatase TiO2 enhances the catalytic activity of MAO/Zirconocene (Zr) complex while rutile TiO2 has a detrimental effect [W. Owpradit, B. Jongsomjit, Mater. Chem. Phys. 112 (2008) 954—incorporated herein by reference in its entirety]. Kaleel et al. reported that an optimum amount of Manganese (Mn) doped TiO2 and organically modified montmorillonite increased activity of MAO/Zr catalyst [S. H. Abdul Kaleel, B. Kottukkal Bahuleyan, S. K. De, M. Jabarulla Khan, R. Sougrat, M. a. Al-Harthi, J. Ind. Eng. Chem. 18 (2012) 1836; G. Leone, F. Bertini, M. Canetti, L. Boggioni, P. Stagnaro, I. Tritto, (2008) 5390—each incorporated herein by reference in its entirety]. Similarly, nano-silica (SiO2), nano-zinc oxide (ZnO), and nano-Zirconia (ZrO2) also enhanced the activity of MAO/Zr catalyst for ethylene/a-olefin polymerization [E. Chaichana, B. Jongsomjit, P. Praserthdam, Chem. Eng. Sci. 62 (2007) 899; E. Chaichana, A. Ngowthanawat, O. Mekasuwandumrong, J. Panpranot, A. Shotipruk, B. Jongsomjit, Iran. Polym. J. 21 (2011) 51; N. M. Ushakov, G. Y. Yurkov, L. V. Gorobinskii, O. V. Popkov, I. D. Kosobudskii, Acta Mater. 56 (2008) 2336; T. Pothirat, B. Jongsomjit, P. Praserthdam, Catal. Commun. 9 (2008) 1426—each incorporated herein by reference in its entirety].
In view of the forgoing, one object of the present disclosure is to provide a catalyst composition having improved catalyst performance and to demonstrate the effect of a barium ferrite nanofiller on the catalytic activity of a metallocene/zirconocene ethylene polymerization catalyst and further a process to synthesize a polyethylene/BaFe12O19 nanocomposite polymer using an in-situ polymerization method.